Textured water sports board

ABSTRACT

The bottom and side surfaces of a water sports board are textured with dimples measuring four to six thousands of an inch deep and a density of 80 to 160 dimples per square inch.

This is a continuation-in-part of application Ser. No. 473,423 filedFeb. 1, 1990, now U.S. Pat. No. 5,052,963 issued Oct. 1, 1991.

TECHNICAL FIELD

This invention relates to water sports boards such as skis, surf boards,knee boards, wind surfers, and the like designed for movement over wateror other viscous or liquid media, and, more particularly to a contactsurface treatment for such devices for enhancing the performancethereof.

BACKGROUND OF THE INVENTION

The contact surface treatment of, for example, skis, to improve theirperformance, is well known in the art. It has been found that the normalsmooth bottom on such devices does not produce the best results, such abottom introducing a viscous drag factor that is undesirable. Efforts toreduce the drag on the surface of the ski that contacts the supportingmedium have primarily been directed to creating a three-dimensionalsurface having a plurality of sloped portions, with the slope orientedin the intended direction of travel of the ski. One example of such astructure is shown in U.S. Pat. No. 3,408,086 of Bennett whereinoverlapping scales are formed on the bottom of the ski which function asthe contact surface. The scales are sloped to reduce friction or drag.Adjacent scales form a series of groove-like configurations whichenhance the directional stability of the ski and enable the operator toexercise a good degree of control, especially in turns. Such a structurehowever is unusually complex and is subject to compaction of thematerial over which the ski is moving. This compaction is reduced by notextending the scale pattern all of the way out to the edges of the ski,but at the cost of leaving the edges of the ski untreated. Thus theadvantages gained from the treatment are not available for highperformance skiing involving numerous turns and rapid changes ofdirection where the ski edges are called upon to function as contactsurfaces.

Variations on the scale construction are shown in U.S. Pat. Nos.4,323,265 of Benner, 4,178,012 of Roth et al, 3,874,315 of Wright and2,914,335 of Rivard. Nevertheless, all of the foregoing prior artarrangements rely upon sloping surfaces to decrease friction or drag,which are, in most cases, unduly complex and difficult to form, and arenot readily applicable to the ski edges or to the edges of water sportsboards such as surf boards, knee boards and wind surfers.

Another approach to reducing drag is based upon the catamaran principle,wherein the contact surface of the ski or other device is formed withtwo or more longitudinally extending ribs. Such a configuration,examples of which are shown in U.S. Pat. Nos. 3,428,979 of Johnson,3,761,980 of Silverstein, 3,827,096 of Brownson and 3,077,617 ofSteffel, reduces the area in contact with the ski supporting snow orwater, thereby reducing drag, and enhances the longitudinal stability ofthe device. As in the case of the sloping surfaces or scales, there isno treatment of the ski edges. Hence these arrangements are unsuitablefor competition or high performance type skis and boards. In addition,these ribs often tend to resist changes in direction, which makes theski or board unsuitable for competitive use.

SUMMARY OF THE INVENTION

The principles of the present invention are applied to a preferredembodiment which comprises a water ski for use in high performanceapplications, such as competition events. The water ski comprises agenerally flat upper surface and a concave lower, water contact surfacewhich also defines the ski edges or sides. In accordance with principlesof the present invention, both the ski sides and the ski bottom areconsidered to constitute the contact surface, and are textured with apattern of elongated dimples, approximately four to six thousandths ofan inch (mils) deep. The dimples may be in the form of elongatedhexagons, rectangles, or ovals, or other suitable shape, interleavedwith each other so that succeeding rows of dimples are laterally offsetfrom the preceding and following rows, in the manner of a honeycomb. Thedensity of the dimple pattern is within the range of 80 to 160 dimplesper square inch. The texture surface does not, of itself, impartsignificant directional stability, hence it is not necessary that thedimples be oriented in any particular direction. The concavity of theski bottom does afford a degree of directional stability sufficient forcompetition skiing, where a high degree of directional stability inneither necessary nor desirable.

In competitive water skiing, such as slalom skiing, the rapidlyoccurring turns and changes in direction require that the ski edgesoften perform as the contact surface. Thus it is desirable that a smoothtransition takes place when the skier goes from upright position to anearly horizontal position as he or she leans into a turn. When thisoccurs, the ski contact surface changes from the bottom of the ski tothe edge of the ski and then back as the skier emerges from the turn.The dimpled texture of the ski contact surface creates a cushion of airbetween the water and the ski, whether the ski is riding on the skibottom or is upon its edge. Hence there is no change in resistance ordrag as the skier negotiates a slalom course. This cushion of air isanalogous to the phenomenon known as "hydroplaning" in automobile tires,wherein tire contact with the road is greatly reduced on wet pavement athigh speeds due to an air cushion build up. With a similar effect on theskis, drag is greatly reduced, as is "chatter" , a phenomenon occurringin rough water which impairs ski performance.

The invention is also applicable to water sports boards such as surfboards, knee boards and wind surfer boards. These boards have an uppersurface and a lower surface, a front end and a rear end, and side edges.The lower surface and sides form a substantially continuous contactsurface which extends substantially the entire length of the board. Thecontact surface is textured with a pattern of dimples that have a depthof approximately four to six thousandths of an inch.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a water ski embodying principles of thepresent invention.

FIG. 2 is a cross-sectional view of the ski of FIG. 1 taken along theline A--A of FIG. 1.

FIG. 3 is a fragmented, perspective view of the ski of FIG. 1.

FIGS. 4 through 7 are diagrammatic views of different texture patternsfor use with the ski of FIG. 1.

FIG. 8 is a perspective view of the top side of a knee board type watersports board embodying principles of the present invention.

FIG. 9 is a perspective view of the bottom of the knee board of FIG. 8.

FIG. 10 is a perspective view of the top side of a surf board or windsurfer board type water sports board embodying principles of the presentinvention.

FIG. 11 is a perspective view of a rear end portion of the bottom of thesurf board of FIG. 10.

DETAILED DESCRIPTION

With reference next to the drawing, in FIG. 1 there is shown a water ski11 embodying principles of the invention. Ski 11 has an upper surfacemember 12 upon which are mounted foot restraints 13, 14 and 16preferably made of rubber or other flexible material. The materialforming member 12 is preferably semi-rigid plastic material of, forexample, the material known as ABS which is commonly used in water skis.Ski 11 has a contact surface 17 and side edges 18, 18 and an up-turnedfront tip 19.

Attached to the underside of member 12, as by epoxy cement, is a hollowfiberglass member 21 which is filled with a core 22 of cellular materialsuch as, for example, polyurethane foam. Member 21 is formed with aconcave bottom along which are attached a plurality of spaced strips 23,23 of Kevlar or graphite which extend from the tip of the ski forapproximately two-thirds of the length thereof. Strips 23 are flexibleand rebound readily from shocks to the ski during use, whilestrengthening the ski. A fiberglass layer 24 covers strips 23 and iscemented to the bottom of member 21, preserving the concave shape, asshown. A plurality of ceramic strips 26, 26 are attached to the bottomof layer 24, and like strips 23, extend approximately two-thirds of thelength of the ski from the tip 19 thereof. Ceramic strips 26, 26strengthen the ski and preserve its shape under stresses, whilefunctioning to absorb shocks during use. A second fiberglass layer 27covers the strips 26, 26 and is affixed to the bottom of layer 24,preserving the concavity, as shown. The strips 23, 23 and 26, 26 imparta stiffness to the front portion of the ski while leaving the rearportion flexible, or "soft", which is desirable in high performanceskis.

The entire assembly shown in FIG. 2 has the various contacting surfacescoated with epoxy and is formed into a unitary structure by being placedin a heated pressure mold until the epoxy is cured.

In accordance with the present invention, that portion of the molddefining the bottom 17 and sides 18, 18 of the ski is textured. Duringthe pressuring and heating of the ski this texture is imparted to thebottom 17 and sides 18, 18, as shown in FIG. 3. Preferably, the texturedsurfaces imparted to the ski extend the entire length thereof, alongboth bottom and sides, with the texture pattern extending completelyacross the bottom 17 and up the sides 18, 18 as seen in FIG. 3.

The texture pattern comprises a plurality of dimples, approximately fourto six mils deep, of any of a number of shapes, as shown in FIGS. 4through 7. In FIG. 4, the dimples 31 are in the shape of elongatedhexagons, with adjacent rows offset to form a honeycomb pattern, asshown. An alternative dimple shape is shown in FIG. 5 wherein thedimples 31 are elliptical or oval in shape, and are interleaved by thetransverse offset of adjacent rows. FIGS. 6 and 7 show dimples 31 in theshape of rectangles, with adjacent rows offset, as shown in FIG. 6, orinterleaved in the manner of a brick walk, as shown in FIG. 7. In thepattern of FIG. 7, adjacent rows of dimples 31 are transversely offsetas well as laterally adjacent dimples being longitudinally offset fromeach other. In each of the patterns shown, the density of the dimples iswithin the range of 80 to 160 dimples per square inch.

It has been found that a dimple pattern such as that shown in FIG. 4,with the dimples approximately six mils deep and having a density ofapproximately 120 dimples per square inch, produces a material reductionin the drag of the ski on the water, and that in sharp turns where theedge of the ski becomes the contact surface, there is no discernibleincrease in drag. In slalom type water skiing, a hole is created in thesharp turn, and the ski of the present invention accelerates out of thehole quickly. In rough or choppy water, a ski tends to "chatter" as itpasses across the chop, or as it passes across the boat wake. Thischatter reduces performance, and is disconcerting to the skier. With thestructure of the present invention, "chatter" is reduced to a manageablelevel with a minimum of decrease in performance or speed.

Verification tests were conducted using a 1988 Correct Craft SkiNautique ski boat. A 60 foot ski rope was tied to a measuring devicethat itself was coupled to the boat stern. The measuring device was aBourdon Tube 30 lbs. strain gauge placed on a standard hydraulic 2' borecylinder with a 5/8' diameter piston rod that netted a 2.835 square incharea.

Two skiers were pulled directly behind the boat at a constant speed of36 mph in a linear direction using a 6 lbs. 12 oz. dimple ski and a 7lbs. 3 oz. undimpled ski. A 130 lb. skier was found to produce a 57.551lb. force on the gauge but only 52.164 lbs with the dimple ski. A 210lbs. skier produced a force of 87.885 lbs. with an undimpled ski and80.514 lbs with the dimple ski.

With reference next to FIGS. 8 and 9 there is shown a knee board typewater sports board 38 having an elongated shell 39. Shell 39 has anupper surface 41 upon which a support pad 42 and a restraining strap 43are mounted. Shell 39 also has a bottom surface 46 and right and leftsides 47 forming a substantially continuous contact surface 48, anup-turned front 49 and a rear end.

The shell is manufactured by conventional blow molding and rotationalmolding techniques which use multiple piece molds. One mold has anegatively textured interior surface shaped to form the bottom surface46 and a lower portion of the sides 47. The other mold piece has aninterior surface shaped to form the remainder of the sides 47 and theupper surface 41 of the shell. Molten plastic is injected into the moldthereby covering its interior surfaces. The molten plastic is cooled onthe mold and thereby hardened to form the shell 39. Finally, the moldpieces are separated and the shell removed from the mold.

In accordance with the present invention, that portion of the molddefining the bottom surface 46 and a lower portion of the sides 47 ofthe shell 39 is textured with a pattern which comprises a plurality ofdimples, as previously described. Preferably, the textured surfaces ofthe shell extend the entire length thereof, along both bottom and sides,with the texture pattern extending completely across the bottom 46 and alower portion of the sides 47 including the front and rear ends.

Finally with reference to FIGS. 10 and 11 there is shown a surf boardtype water sports board 55. It should be noted that this type of boardis also used as a wind surfer board, the difference being that a sailingrig 61 is mounted to the board, a bottom portion of which is shown inFIG. 10. The board has an elongated shell 56 which has an upper surface57, a bottom surface 58 and sides 59. The bottom surface 58 and sides 59form a substantially continuous water contact surface 60.

These shells are preferably manufactured in two ways. One way is tolayer fiberglass about a foam core, similar to the way in which thewater ski is manufactured as previously described. The other way is toform a plastic shell in the same manner as previously described inreference to the manufacture of knee boards.

Again, in accordance with the present invention, the bottom surface 58and a lower portion of the sides 59 are textured with a pattern ofdimples, as previously described. Preferably, the textured surfacesimparted to the shell extend the entire length thereof, with the texturepattern extending completely across the bottom 58 and the lower portionof the sides 59, including the front and rear ends. The texture patterncomprises a plurality of dimples as previously described.

It thus is seen that water skis and water sports boards are now providedwith reduced drag. It should be understood that the just describedembodiments merely illustrate principles of the invention in preferredforms. Many modifications, additions and deletions may be made withoutdeparture from the spirit and scope of the invention as set forth in thefollowing claims.

I claim:
 1. A water sports board such as a surf board, a knee board or awind surfing board comprising an elongated member having an uppersurface and a lower surface, a front end and a rear end, and first andsecond sides, said lower surface and at least lower portions of saidsides forming a substantially continuous contact surface, said contactsurface being textured with a pattern of dimples with each dimple havinga depth of approximately four to six thousandths of an inch, saidcontact surface extending substantially the entire length of said watersports board.
 2. The water sports board as claimed in claim 1 whereinthe density of said dimples in said pattern is in the range of 80 to 160dimples per square inch of contact surface.
 3. The water sports board asclaimed in claim 2 wherein the density of said dimples in said patternis 120 dimples per square inch of contact surface.
 4. The water sportsboard as claimed in claim 1 wherein said dimples in said pattern arearranged in rows with adjacent rows being laterally offset from eachother.
 5. The water sports board as claimed in claim 4 wherein saiddimples are in the shape of elongated hexagons.
 6. The water sportsboard as claimed in claim 4 wherein said dimples are in the shape ofellipses.
 7. The water ski as claimed in claim 4 wherein said dimplesare in the shape of longitudinally oriented rectangles.
 8. The watersports board as claimed in claim 7 wherein laterally adjacent dimplesare longitudinally offset from each other.
 9. The water sports board asclaimed in claim 1 wherein substantially the entire lower portion ofsaid first and second sides is textured with said dimples.
 10. The watersports board as claimed in claim 1 wherein substantially the entiresurface of said contact surface is textured with said dimples.